1. Field of the Invention
The present application relates to feed additives for ruminant animals.
2. Description of Related Art
It has long been known to provide additives in the feed of ruminant animals such as cattle, sheep, and goats to improve the rumen (first stomach) function, particularly for ruminant animals that are fed high levels of concentrated grain diets to increase milk production in milk-producing animals and improve meat conversion in meat animals.
Ruminant animals have a unique digestive system. Microorganisms found in the rumen allow the animals to manufacture protein amino acid from the fermentation of forage and grains. Byproducts from the fermentation process are volatile fatty acids (VFA) and ammonium ions (ammonia). VFA and ammonia are essential in the digestive process. They form the building blocks for protein synthesis and utilization of nutrients for the proper metabolic processes of the animal. However, in elevated quantities, either of these two products impair the efficiency of rumen digestion and can even cause the death of the animal. Ailments related to acid imbalance are acidosis, rumenitis, laminitis, anorexia and liver abscess. Ammonia, which is produced naturally by the rumen microorganisms, is utilized to synthesize cellular protein. When high levels of ammonia occur, the acid-base balance of the blood changes and toxic symptoms such as incoordination, labored breathing, and convulsions may affect the animal. The animal's natural mechanism to regulate rumen pH is the secretion of saliva containing sodium bicarbonate and potassium bicarbonate.
Current herd management techniques stress the feeding of high levels of concentrated grain diets. However, the large quantities of highly fermentable grains lead to rapid production of VFA's and to decreased production of saliva. Acid buffering of animal feed by the addition of sodium bicarbonate, sodium sesquicarbonate, dolomite, or magnesium oxide, then, is common practice.
Sodium bicarbonate and sodium sesquicarbonate are effective pH buffers in aqueous solutions, but they have several drawbacks in the rumen system. They are water soluble and may be flushed out of the rumen before the typical 14-hour to 16-hour rumen turnover time. Additionally, bicarbonate flushed through the intestinal tract is not sufficient to deal with the large volume of acid digestia leaving the abomasum. Also, some nutritionists claim that the palatability of feed is reduced by the addition of sodium bicarbonate. The high sodium content of these two products may stress the cardiovascular system by increasing central venous pressure resulting in hypertension. A much less expensive source of dietary sodium is available for rations with sodium chloride (NaCl, table salt). Sodium bicarbonate and sodium sesquicarbonate generate carbon dioxide gas as they decompose in the rumen and neutralize acid. The carbon dioxide gas passes out of the rumen, through the animal's esophagus to the environment. Carbon dioxide is a greenhouse gas and its emission is being considered for regulation by some governmental agencies. Additionally, sodium bicarbonate is a manufactured product that requires considerable energy and cost to produce.
Dolomite (calcium, magnesium limestone) is an effective, natural mineral buffer at low pH, but its activity decreases above pH 5.6. Optimal rumen pH is 6.1 to 6.8. Dolomite is also a carbonate and it produces carbon dioxide as it neutralizes acid in the animal.
Magnesium oxide in feed rations at the proper dose provides bio-available magnesium to the animal and can be an important nutrient source. Certain grades of non-refractory magnesium oxide are also good pH buffers for control of excess rumen acid. Animal feed grade magnesium oxides generally are produced from natural brines or by calcining natural magnesite (magnesium carbonate). These processes are energy intensive and expensive. Feed grade magnesium oxide generally costs two to three times more than sodium bicarbonate, and costs four to six times more than feed grade dolomite. Commercial practice is to minimize the use of expensive magnesium oxide. Other less expensive sources of bio-available magnesium are in demand.
Although sodium bicarbonate, sodium sesquicarbonate, and magnesium oxide in proper doses buffer the rumen from acidosis (high acid, low pH), they do not control excess ammonia produced by the microorganisms, nor do they reduce the negative affect of mold toxins (mycotoxins) that may occasionally occur in feed rations.
Products currently used to control ammonia toxicity are ion exchange materials such as synthetic and natural zeolites.
White, et. al., Canadian Patent No. 939,186, issued Jan. 1, 1974 teaches the use of zeolites to reduce the effects of high ammonium production in the rumen when animals were fed urea or non-protein nitrogen compounds.
Chu, et. al., U.S. Pat. No. 5,079,201, issued Jan. 7, 1992, describes a composition of clay and zeolite for the absorption of ammonium ions in order to lower the amount of ammonia passed to the liver from the alimentary canal.
Coincidentally, it has been found that certain naturally occurring zeolites absorb and bind aflatoxin and other mycotoxins present in mold contaminated feeds and are therefore beneficial as feed additives.
Scheidler, S., 1993, Effects of Various Types of Alumino-Silicates and Aflatoxin B, Chick Performance and Mineral Studies, Poultry Sci., 72:282-288 teaches that certain natural zeolite minerals and other alumino-silicates reduce the negative effects of poultry fed a diet containing mycotoxin (Aflatoxin B).
Schell, et. al., 1993, Effectiveness of Different Types of Clay for Reducing the Detrimental Effects of Aflatoxin-Contaminated Diets on Performance and Serum Profiles of Weanling Pigs, J. Animal Sci. 71:1226-31 teaches that certain absorptive clays and at least one natural zeolite added to feed rations overcome the negative effects of feed containing aflatoxin as a contaminant.
Dolomitic hydrated lime, also know as Type-S lime, dolomitic hydrated lime, or calcium-magnesium lime hydrate, is a common industrial product presently used in cement plaster formulations and to neutralize acidic wastes. Dolomitic hydrated lime is not known to be used in animal feed rations. The taste is sharp or bitter, as is the case with many calcined lime products or their derivatives, and attempts to feed it in the past have resulted in adverse conditions of reduced feed intake, loose stools, or diarrhea. Indeed, the Material Safety Data Sheet published by Graymont Dolime, Inc. of Genoa, Ohio in September 2006 for dolomitic hydrated lime warns of exposure from contact causing severe irritation to skin, mucous membranes, and the eyes. It also warns of ingestion hazards of pain, vomiting blood, diarrhea, and collapse or drop in blood pressure.
Thus, although the foregoing products and methods represent great strides in the area of feed additives for ruminant animals, many shortcomings remain.